The present invention relates to medical equipment, techniques and procedures, and more particularly, to the circulation and recovery of blood during and immediately following heart bypass surgery.
A persistent dilemma is faced hundreds of times each day worldwide, of how to handle the volume of a patient""s blood in the circuit of a cardiac pulmonary bypass system (heart-lung machine), after the surgical procedure has been completed and the patient is disconnected from the bypass system.
One option is to transfuse the volume in the cardiopulmonary bypass (CPB) circuit to the patient, in the manner of a blood transfusion, without compromising the integrity of the bypass system. It should be appreciated that the CPB circuit includes a crystalloid priming fluid which is necessary to initiate the pumping of the circuit. Therefore, transfusion of the content of the circuit would include transfusion of the priming solution which, by the end of the surgery, has been fully mi,(ed with the patient""s own blood. The hematocrit concentration is therefore low, i.e., approximately 18-23%. Although some such diluted blood can be transfused to the patient, a relatively large fraction of the volume of the CPB circuit cannot be transfused, because this volume is needed to maintain the integrity of the circuit in the event full bypass is to be resumed.
Alternatively, the content of the CPB circuit can be transferred to sterile blood bags, for a possible re-transfusion to the patient either in or out of the operating room. This option also suffers from the dilution of important blood components and the need to keep a large fraction of the diluted blood in the circuit to maintain circuit integrity.
Yet a third option, is to chase all the volume in the CPB circuit with a crystalloid solution to a so-called xe2x80x9ccell saverxe2x80x9d, where the fluid volume is separated into red blood cells and effluent. Although the red blood cells are saved, the effluent is deemed waste and therefore discarded, yet the effluent contains many desirable constituents of whole blood, such as plasma, platelets, clotting factors, etc.
Finally, the most straight-forward option is to seal or drain and discard the content of the CPB circuit. This is common in pediatric open heart cases, but benefits neither the patient nor anyone else, and presents a significant disposal problem to the perfusionist (i.e., the operator of the heart/lung machine), who must clean up and discard this wasted volume.
Because in the foregoing options, the patient cannot receive his own entire blood volume from the CPB circuit immediately following cardiac or thoracic vascular procedures, if the need for additional blood arises, the only available source is from previously stored blood bags. If the patient gave blood prior to surgery, which is rare, then the patient could receive so-called autologous blood. Most often, however, such additional blood or blood products would be provided from a dwindling blood bank supply, which originated from an allogenic (unknown) donor. Transfusing such blood can arouse anxiety and create problems including hemolytic reactions, viral hepatitis-C, and potentially, blood viruses or AIDS. Human error can occur when mistakes are made by giving non-compatible or mislabelled blood products. Lastly, there is also a small population of patients that completely refuse any foreign blood or blood products of any kind, due for example, to religious beliefs.
Because of these reasons, the need exists to reduce allogenic blood use and strive for xe2x80x9cbloodless surgeryxe2x80x9d.
It is an object of the present invention to provide a method and blood bag, whereby a substantial volume of concentrated whole blood can be quickly and easily recovered from the CPB circuit of a patient immediately following cardiac or thoracic vascular surgery.
It is a further object of the invention, that such recovered blood be available in the operating room for rapid volume replacement and stability of the patient.
It is yet another object of the invention, that the blood be recovered from the CPB circuit while ensuring that the cardiopulmonary bypass circuit remains de-aired and ready for immediate reuse in the event cardiopulmonary bypass assistance for the patient must be resumed.
It is still another object of the invention to provide a bag system for receiving the patient""s blood in the field of surgery, and concentrating the blood outside the field for storage in the bag, which can be conveniently handled in or outside the operating room for transfusion to the patient either in or outside the operating room.
These and other objects can be achieved in an operating room, by transferring most of the blood in the CPB circuit into a sterile bag located in the surgical field, removing the bag with blood from the surgical field, and outside the surgical field, but preferably in the operating room, hemo-concentrating the blood in the bag, while the bag is fluidly connected to the bypass system hardware.
The inventive method according to the invention, can also be considered as including the steps after the bypass system connections have been removed from the patient, of first, fluidly connecting the CPB circuit outlet e.g., arterial line, downstream of the arterial pump to a sterile blood bag. The blood in the CPB circuit is then chased into the blood bag with, e.g., crystalloid solution. The blood bag is fluidly connected to a closed hemoconcentration circuit, and when the hematocrit concentration of the blood in the bag reaches a desired value, the bag is sealed, labelled, and made available for transfusion to the patient either in or out of the operating room.
A novel blood bag (or hemo-bag) system is especially adapted for use with the method of the present invention. The new hemo-bag system comprises a closed, sterile bag of substantially transparent, bio-compatible material, defining upper and lower ends. An infusion port is located at the upper end of the bag. An outlet port, an inlet port, and an IV line are situated at the lower end of the bag. A baffle is preferably located inside the bag, for directing upward flow entering the s bag through the inlet port, away from the outlet port. Each of the ports and line terminate in connector structure, and can be opened or closed by way of conventional clips and caps.
The preferred method according to the invention is implemented after cardiopulmonary bypass has ceased, and the cannulas connected to the CPB circuit have been removed from the patient. The venous line of the CPB circuit can be drained backward with crystalloid solution, from a bucket on the field, and then clamped, keeping the venous line intact with priming fluid, for use in the event a restart of the bypass system for the patient, becomes necessary. The arterial line cannula is removed from the patient and circuit, and the arterial line is connected to the infusion port at the top of the hemo-bag, while all the clips on the ports and lines at the bottom of the hemo-bag are closed and capped. Volume from the CPB circuit is then chased with crystalloid solution through the CPB circuit, filling the hemo-bag with the patient""s blood from the circuit. Both the arterial line and the infusion port at the top of the hemo-bag are then clamped. An appropriately sized connector with a Luer can be placed between the venous and arterial lines and fluid recirculated so the CPB circuit remains intact (i.e., with enough priming fluid to resume pumping without ingress of air), thereby protecting its integrity for reinstitution of bypass if necessary. Once the dead end cap is on the infusion port the hemo-bag becomes a sterile closed container of the patient""s blood which can be handed off the field of surgery, to the perfusionist, outside the field of surgery.
The perfusionist then connects the hemo-bag to a hemo-concentrator, such that the blood from the outlet port at the bottom of the hemo-bag flows into the hemo-concentrator and the concentrated blood flow from the hemo-concentrator enters the inlet port at the bottom of the bag. Typically, a spare roller pump in the console of the cardiopulmonary bypass system is used to actively circulate the blood, in this hemo-concentration circuit.
Once the concentration reaches a satisfactory level, the outlet port of the hemo-bag is clamped off and, preferably, the blood in the recirculation circuit is chased into the bag as the pump operates, by allowing air through, for example, a Luer port near the closed outlet port of the bag. Once air enters the hemo-bag, the pump is stopped, the bag inlet port is then clamped off, the hemo-concentrator is disconnected, and the caps on the bottom are reclosed. The hemo-bag is labelled for the patient and handed up to the anesthesiologist at the head of the patient, where, if necessary, the IV line can be spiked and the hemo-concentrated whole blood can be infused in a timely manner. This benefits the patient by saving time, money, and in many cases, eliminating the need for and anxiety associated with, allogenic blood bank products. Alternatively, the hemo-bag can be easily transported for later transfusion into the patient, as necessary after the patient has been removed from the operating room.